While she was playing the clinically cool Agent Scully on the TV series "The X Files," Gillian Anderson was fleeing her own demons.

She says she suffered severe panic attacks while pregnant with daughter Piper, now 11. She still suffers from a fear of being trapped.

"It's anything that makes me feel trapped," she says, reclining on a bed in her hotel room in Pasadena, Calif., her bare feet tucked under the covers.

"And sometimes that can happen on stage, and sometimes that can happen on a film when there is a scene that has to do with special effects, or has to do with something where you're trapped in a situation you can't get out of — like having to do take after take after take after take, like going up and down a hill or doing something like that. It makes me want to scream," she shudders.

A bad back has temporarily grounded Anderson, who is propped uncomfortably on two pillows, a burned-out cigarette in her left hand, a can of Coke on the bedside table.

That abiding threat may be why she's is so good in "Bleak House," the Dickens classic premiering Sunday on PBS' "Masterpiece Theatre." Anderson plays the tragic Lady Deadlock, an aristocrat trapped by her past.

From her placid exterior and flawless face, it's hard to imagine Anderson as anything but collected, especially when she was playing the dark-suited, buttoned-down Scully.

"I had a very difficult and challenging pregnancy and started to have panic attacks, and they lasted about a year," she says.

"I'd have them one or two times a day, and they lasted for hours. That was while I was filming 'The X-Files' and was pregnant and a new mother. They were so terrifying. I thought I was going insane! It made me think about the fragility of life in a different way.

"I'm not afraid of death," she muses. "I'm afraid of panic attacks. It made me have to ground myself at that time in a completely different way. It made me more sympathetic to other human beings.

"It's slowed everything down in a way."

The panic episodes lasted until a few months after her daughter was born.

"I was working with a therapist for a while over the phone. My therapist was in L.A., and we were in Vancouver. I was trying to find different ways to train my brain not to run with it when I get triggered. That's the trouble with panic attacks, once they start, then you start shaking in a panic attack. And if you get a chill — just from an air conditioner — your body will think it's a panic attack and it will go into a panic attack.

"It's such a horrible cycle to be in. I had to work really hard at calming my brain and my mind, and not allowing it to go into those dark areas. My brain still goes into dark areas."

She pauses.

"I've had some more experience with something similar in the past year, and it continues to remind me how fragile we are."

Fragile, yes, but Anderson always has been a rebel. At 15, she dug deeply into the punk ethos and was constantly in trouble. But a role in community theater changed all that.

"When I did this play and experienced the stage experience with an audience, it transformed me, and all of a sudden my grades went up. I started to study. It was like a piece of the puzzle had been put in," she says.

"The X-Files" proved to be life-altering, too. "I'd hardly done anything, and I had no money, and I was living with a boyfriend at the time and had just received my last unemployment check," she says, relighting the cigarette and readjusting her position.

"And all of a sudden, within a week, I was transported up to another country, paid money I'd never seen before. And that started the path of living in Canada, meeting my (first) husband, getting pregnant, being on a hit series, divorce, fame, everything. The receiving of that script was a turning point."

Anderson, 37, married her longtime sweetheart, Kenya-born documentarian Julian Ozanne, a year and a half ago and lives in London.

"It's hard to say what he really does," she laughs. "Right now he's doing carbon trading and reforestry."

One would think that nine years on one of the most successful TV shows in history would make Anderson a hot commodity in Hollywood. But she says that's not so.

"In England, I get offered films. The films that I've turned down are probably ones that you will never hear of," she says.

"I don't get offers in America. People don't know what to do with me in America. And I've disappeared. And so, to be absolutely honest with you, it's not a situation of saying, 'Oh, they offered me "Proof," but I said no, so they went to Gwenyth Paltrow.' It's just not a part of my life. I think perhaps there's a slight perception that I was a temporary television celebrity who disappeared off the face of the planet."